Yes, users must follow both ‘Required specification’ if you cannot follow the power-down sequence recommended specification. You must ensure all power rails fully power down within 100ms with following requirements:
a. Required Power-Down Ramp Specification – all Group 2 and Group 3 supplies must be under 1.0V whenever any Group 1 supply goes under 0.35V. You can refer to AN 692 document for the different power groups.
b. Required Voltage Differential Specification – any two power supplies between different power groups during power-down is meeting the voltage differential specification: ΔV < ΔVnom + 500 mV